Surface Water Management Division
Lake Cassidy
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Lake Cassidy is located north of Lake Stevens and three miles east of Marysville. The lake covers 125 acres with an average depth of 3.4 meters. The watershed covers 2,477 acres with about 18% developed. There is a public boat launch located on the southwest shore. The Centennial Trail also runs along the eastern shoreline which includes the Lake Cassidy Wetlands Park & Interpretive Trail. Power boats are permitted but only with a maximum speed of 8 mph and a maximum horsepower of 10. |
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Summary
Lake Cassidy has high nutrient levels, abundant algae, low water clarity, and dense aquatic plants. Although the lake provides valuable recreation and aesthetic enjoyment, these conditions impair the use of the lake at times. Preservation of nearby wetlands and careful development in the watershed are important for protecting the health of the lake.
Reports
A comprehensive Snohomish County State of the Lakes Report was produced in 2003 and includes a specific section on Lake Cassidy. Individual lake updates to this report are provided each year as new data are collected.
Data
Snohomish County Surface Water Management (SWM) together with volunteer lake-monitors have been collecting water quality data for Lake Cassidy since 1994. Current and historical lake water quality data are available online in SWM's interactive Water Quality Database.
Lake Cassidy Maps
- Bathymetric Map - this map shows contour lines of equal depth similar to a topographic map. Public access sites are also indicated on each map when applicable.
- Aerial Photo - 2007 aerial photos of the lake with relevant features such as public access sites and nearby roads.
- Watershed Map - this map shows the boundary of the Lake Cassidy watershed. A watershed is the land area that drains into the lake.
Lake Cassidy Toxic Algae Monitoring
Lake Cassidy has been monitored since 2008 for potentially toxic algae blooms that typically occur in the summer and fall. The following are links to information on the sampling projects and the most recent test results.
Lake Cassidy Resources
Contact
Gene Williams, Senior Planner, 425-388-3464 extension 4563
Marisa Burghdoff, Water Quality Analyst, 425-388-3464 extension 4639
Some documents are in pdf format. To read these files you'll need to have Adobe Acrobat Reader installed on your computer.